Drilling apparatus with shutter

ABSTRACT

The present disclosure relates to a drilling apparatus including a cutting unit defining at least one through-hole that provides fluid communication between a distal side and a proximal side of the cutting unit. The cutting unit includes a plurality of cutting elements at the distal side of the cutting unit. The cutting unit also includes a shutter for selectively opening and blocking the through-hole of the cutting unit.

This application is being filed on 15 Mar. 2010, as a PCT InternationalPatent application in the name of Vermeer Manufacturing Company, a U.S.national corporation, applicant for the designation of all countriesexcept the US, and Keith Allen Hoelting, a citizen of the U.S., AndisSalins and Stuart Harrison, both citizens of Australia, applicants forthe designation of the US only.

TECHNICAL FIELD

The present disclosure relates generally to trenchless drillingequipment. More particularly, the present disclosure relates to drillingequipment capable of maintaining a precise grade and line.

BACKGROUND

Modern installation techniques provide for the underground installationof services required for community infrastructure. Sewage, water,electricity, gas and telecommunication services are increasingly beingplaced underground for improved safety and to create more visuallypleasing surroundings that are not cluttered with visible services.

One method for installing underground services involves excavating anopen trench. However, this process is time consuming and is notpractical in areas supporting existing construction. Other methods forinstalling underground services involve boring a horizontal undergroundhole. However, most underground drilling operations are relativelyinaccurate and unsuitable for applications on grade and on line.

PCT International Publication No. WO 2007/143773 discloses amicro-tunneling system and apparatus capable of boring and reaming anunderground micro-tunnel at precise grade and line. While this systemrepresents a significant advance over most prior art systems, furtherenhancements can be utilized to achieve even better performance.

SUMMARY

One aspect of the present disclosure relates to a drilling apparatusincluding a cutting unit defining at least one through-hole thatprovides fluid communication between a distal side and a proximal sideof the cutting unit. In use, spoils generated by the cutting unit can bedrawn through the through-hole by a vacuum of the drilling apparatus.The cutting unit also includes a flow-control shutter. In certainembodiments, the shutter is movable between a first position where thethrough-hole is blocked/closed and a second position where thethrough-hole is open/unblocked. In other embodiments, the shutter can beused to only partially block the through-hole. By selecting theportion/percentage of the through-hole that is blocked by the shutter itis possible to enhance drilling performance by customizing the opentransverse cross-sectional area of the through-hole to match the type ofgeologic material in which the drilling apparatus is being used.

Another aspect of the present disclosure relates to a drilling apparatus(i.e., a tunneling apparatus) adapted for use in flowable conditions(e.g., drilling environments below the water table). In certainembodiments, the drilling apparatus includes a drill string having aproximal end and a distal end. A cutting unit is mounted at the distalend of the drill string. The cutting unit is powered by a drivemechanism at the proximal end of the drill string. The drive mechanismis adapted to provide torque for rotating a cutting component of thecutting unit and is also adapted for applying thrust to the drill stringto drive the drill string and the cutting unit distally into the ground.The drill string defines a vacuum passage for evacuating spoilsgenerated by the cutting component within a bore being drilled. Thedrill string also defines an air passage for providing air down the boreduring drilling to reduce the likelihood of plugging of the vacuumpassage. The cutting component defines through-holes that provide fluidcommunication between the vacuum passage and a cutting side (i.e., adistal side) of the cutting component. The through-holes also providefluid communication between the air passage and the cutting side of thecutting component. The cutting unit further includes a shutter forselectively opening and closing the through-holes. During normaldrilling operations in flowable conditions, the through-holes are openthereby allowing: a) spoils generated at the cutting side of the cuttingcomponent to readily be drawn through the through-openings and into thevacuum passage; and b) air from the air passage to flow to the cuttingside of the cutting component. When drilling operations are stopped, theshutter is used to close (i.e., block, cover, etc.) the through-holes toprevent flowable material at the cutting side of the cutting componentfrom filling the vacuum passage and/or the air passage.

A variety of additional aspects will be set forth in the descriptionthat follows. The aspects can relate to individual features and tocombinations of features. It is to be understood that both the foregoinggeneral description and the following detailed description are exemplaryand explanatory only and are not restrictive of the broad inventiveconcepts upon which the embodiments disclosed herein are based.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic depiction of a drilling apparatus having featuresin accordance with the principles of the present disclosure;

FIG. 2 is a side view of a drill head in accordance with the principlesof the present disclosure;

FIG. 3 is a perspective view of the drill head of FIG. 2 showing acutting side (i.e., a distal side) of a rotational cutting componentlocated at a distal end of a cutting unit of the drill head;

FIG. 4 is a perspective view showing a shutter located at a proximal endof the cutting unit of FIG. 3, the shutter and rotational cuttingcomponent are shown in a first relative position in which fluidcommunication between the distal end and the proximal end of the cuttingunit is open;

FIG. 5 is a perspective view showing the shutter and the rotationalcutting component of the cutting unit of FIG. 3 in a second relativeposition in which fluid communication between the distal end and theproximal end of the cutting unit is open;

FIG. 6 is a front, exploded perspective view of another cutting unit inaccordance with the principles of the present disclosure;

FIG. 7 is a rear, exploded perspective view of the cutting unit of FIG.6;

FIG. 8 is a cross-sectional view of an assembled version of the cuttingunit of FIG. 6;

FIG. 9 is a front view of the cutting unit of FIG. 6 in a fully-openflow orientation;

FIG. 10 is a rear view of the cutting unit of FIG. 6 in the fully-openconfiguration;

FIG. 11 is a front view of the cutting unit of FIG. 6 in a partiallyopen flow configuration;

FIG. 12 is a rear view of the cutting unit of FIG. 6 in the partiallyopen flow configuration;

FIG. 13 is a front, perspective, exploded view of a further cutting unitin accordance with the principles of the present disclosure;

FIG. 14 is a rear, perspective, exploded view of the cutting unit ofFIG. 13; and

FIG. 15 is a cross-sectional view of an assembled version of the cuttingunit of FIG. 13.

DETAILED DESCRIPTION A. Overview of Example Drilling Apparatus

FIG. 1 shows a drilling apparatus 20 having features in accordance withthe principles of the present disclosure. Generally, the apparatus 20includes a plurality of pipe sections 22 that are coupled together in anend-to-end relationship to form a drill string 24. Each of the pipesections 22 includes a drive shaft 26 rotatably mounted in an outercasing assembly 28. A drill head 30 is mounted at a distal end (i.e., afront end) of the drill string 24 while a drive unit 32 is located at aproximal end (i.e., a back or rear end) of the drill string 24. Thedrive unit 32 includes a torque driver adapted to apply torque to thedrill string 24 and an axial driver for applying thrust or pull-backforce to the drill string 24. Thrust or pull-back force from the driveunit 32 is transferred between the proximal end and the distal end ofthe drill string 24 by the outer casing assemblies 28 of the pipesections 22. Torque is transferred from the proximal end of the drillstring 24 to the distal end of the drill string 24 by the drive shafts26 of the pipe sections 22 which rotate relative to the casingassemblies 28. The torque from the drive unit 32 that is transferredthrough the apparatus 20 by the drive shafts 26 is ultimately used torotate a cutting unit 34 of the drill head 30.

The pipe sections 22 can also be referred to as drill rods, drill stemsor drill members. The pipe sections are typically used to form anunderground bore, and then are removed from the underground bore whenproduct (e.g., piping) is installed in the bore.

The drill head 30 of the drilling apparatus 20 can include a drive stem46 rotatably mounted within a main body 38 of the drill head 30. Themain body 38 can include a one piece body, or can include multiplepieces or modules coupled together. A distal end of the drive stem 46 isconfigured to transfer torque to the cutting unit 34. For example, thedistal end of the drive stem 46 can include a male torque driver 49(e.g., a hexagonal driver) that fits within a torque driver receptacle51 of the cutting unit 34 (e.g., a hexagonal female socket of thecutting unit 34). A proximal end of the drive stem 46 couples to thedrive shaft 26 of the distal-most pipe section 22 such that torque istransferred from the drive shafts 26 to the drive stem 46. In this way,the drive stem 46 functions as the last leg for transferring torque fromthe drive unit 32 to the cutting unit 34. The outer casing assemblies 28transfer thrust and/or pull back force to the main body 38 of the drillhead. The drill head 30 preferably includes bearings (e.g., axial/thrustbearings and radial bearings) that allow the drive stem 46 to rotaterelative to the main body 38 and also allow thrust or pull-back force tobe transferred from the main body 38 through the drive stem 46 to thecutting unit 34.

In certain embodiments, the drilling apparatus 20 is used to formunderground bores at precise grades. For example, the drilling apparatus20 can be used in the installation of underground pipe installed at aprecise grade. In some embodiments, the drilling apparatus 20 can beused to install underground pipe or other product having an outerdiameter less than 600 mm or less than 300 mm.

It is preferred for the drilling apparatus 20 to include a steeringarrangement adapted for maintaining the bore being drilled by thedrilling apparatus 20 at a precise grade and line. For example,referring to FIG. 1, the drill head 30 includes a steering shell 36mounted over the main body 38 of the drill head 30. Steering of thedrilling apparatus 20 is accomplished by generating radial movementbetween the steering shell 36 and the main body 38 (e.g., with radiallyoriented pistons, one or more bladders, mechanical linkages, screwdrives, etc. positioned between the steering shell 36 and the main body38). Further details about suitable steering systems are provided inU.S. Provisional Patent Application No. 61/246,616, filed Sep. 29, 2009,that is hereby incorporated by reference in its entirety.

Steering of the drilling apparatus 20 is preferably conducted incombination with a guidance system used to ensure the drill string 24proceeds along a precise grade and line. For example, as shown at FIG.1, the guidance system includes a laser 40 that directs a laser beamthrough a continuous axially extending air passage 43 defined by theouter casing assemblies 28 of the pipe sections 22 to a target locatedadjacent the drill head 30. The air passage extends from the proximalend to the distal end of the drill string 24 and allows air to beprovided to the cutting unit 34. An air pressure source 45 can be usedto force air distally through the passage 43.

The drilling apparatus 20 also includes an electronic controller 50(e.g., a computer or other processing device) linked to a user interface52 and a monitor 54. The user interface 52 can include a keyboard,joystick, mouse or other interface device. The controller 50 can alsointerface with a camera 60 such as a video camera that is used as partof the steering system. For example, the camera 60 can generate imagesof the location where the laser beam hits the target. It will beappreciated that the camera 60 can be mounted within the drill head 30or can be mounted outside the drilling apparatus 20 (e.g., adjacent thelaser 40). If the camera 60 is mounted at the drill head 30, data cablecan be run from the camera through a passage that runs from the distalend to the proximal end of the drill string 24 and is defined by theouter casing assemblies 28 of the pipe sections 22. In still otherembodiments, the drilling apparatus 20 may include wireless technologythat allows the controller to remotely communicate with the down-holecamera 60.

During steering of the drilling apparatus 20, the operator can view thecamera-generated image showing the location of the laser beam on thetarget via the monitor 54. Based on where the laser beam hits thetarget, the operator can determine which direction to steer theapparatus to maintain a desired line and grade established by the laserbeam. The operator steers the drill string 24 by using the userinterface to cause a shell driver 39 to modify the relative radialposition of the steering shell 36 and the main body 38 of the drill head30. In one embodiment, a radial steering force/load is applied to thesteering shell 36 in the radial direction opposite to the radialdirection in which it is desired to turn the drill string. For example,if it is desired to steer the drill string 24 upwardly, a downward forcecan be applied to the steering shell 36 which forces the main body 38and the cutting unit 34 upwardly causing the drill string to turnupwardly as the drill string 24 is thrust axially in a forward/distaldirection. Similarly, if it is desired to steer downwardly, an upwardforce can be applied to the steering shell 36 which forces the main body38 and the cutting unit 34 downwardly causing the drill string 24 to besteered downwardly as the drill string 24 is thrust axially in aforward/distal direction.

To assist in drilling, the drilling apparatus 20 can also include afluid pump for forcing drilling fluid from the proximal end to thedistal end of the drill string 24. In certain embodiments, the drillingfluid can be pumped through a central passage defined through the driveshafts 26. The central passage defined through the drive shafts 26 canbe in fluid communication with a plurality of fluid delivery portsprovided at the cutting unit 34 such that the drilling fluid is readilyprovided at a cutting face of the cutting unit 34. Fluid can be providedto the central passage though a fluid swivel located at the drive unit32. In other embodiments, a drilling fluid line can be routed from theproximal end to the distal end of the drill string through a separatechannel defined by the drill string.

The drilling apparatus 20 can also include a vacuum system for removingspoils and drilling fluid from the bore being drilled. For example, thedrill string 24 can include a vacuum passage 47 that extendscontinuously from the proximal end to the distal end of the drill string24. The proximal end of the vacuum passage can be in fluid communicationwith a vacuum 65 and the distal end of the vacuum passage is typicallydirectly behind the cutting unit 34 adjacent the bottom of the bore. Thevacuum 65 applies vacuum pressure to the vacuum passage 47 to removespoils and liquid from the bore being drilled. At least some airprovided to the distal end of the drill string 24 through the airpassage 43 is also typically drawn into the vacuum passage to assist inpreventing plugging of the vacuum passage. In certain embodiments, theliquid and spoils removed from the bore though the vacuum passage can bedelivered to a storage tank 67.

B. Example Cutting Units

FIG. 2 is a side view of a distal portion of the drill head 30 of thedrilling apparatus 20 of FIG. 1. Specifically, FIG. 2 shows the steeringshell 36 and the cutting unit 34 of the drill head 30. The cutting unit34 includes a proximal end 70 (i.e., a back or rear end) positioneddirectly adjacent to a distal end of the steering shell 36 and a distalend 72 (i.e., a front end) distally offset from the steering shell 36.

Referring to FIG. 3, the cutting unit 34 includes a rotational cuttingcomponent 74 that is rotated about a central longitudinal axis 75 (seeFIGS. 4 and 5) of the cutting unit 34 to facilitate cutting a bore withthe drilling apparatus 20. The axis 75 can be co-axially aligned withthe central longitudinal axis defined by the drive shafts 26 of the pipesections 22. Specifically, the rotational cutting component 74 isrotated about the axis 75 via torque transferred from the drive unit 32by the drive shafts 26. During drilling operations, the rotationalcutting component 74 is typically rotated about the axis 75 relative tothe steering shell 36 of the drill head 30, the main body 38 of thedrill head 30 and the casing assemblies 28 of the pipe sections 22.

Referring to FIGS. 3 and 4, the rotational cutting component 74 includesan outer rim 76 (e.g., a cylindrical outer rim) that extends generallyfrom the distal end 72 to the proximal end 70 of the cutting unit 34.The rotational cutting component 74 also includes a front cuttermounting plate 78 (e.g., an annular mounting plate) non-rotationallyconnected to the outer rim 76 adjacent the distal end 72 of the cuttingunit 34. The phrase “non-rotationally connected” means that theconnection does not allow relative rotation between the interconnectedpieces. For example, the front cutter mounting plate 78 can be welded tothe outer rim 76. Alternatively, the front cutter mounting plate 78 canbe unitarily cast with the outer rim 76, machined as an integral partwith the outer rim 76 or attached to the outer rim 76 with fasteners. Asshown at FIG. 3, an outer peripheral portion 77 of the front cuttermounting plate 78 is non-rotationally connected to the outer rim 76.

Referring to FIG. 4, the rotational cutting component 74 also includesan inner hub 80 that is non-rotationally connected to an inner portionof the front cutter mounting plate 78. The inner hub 80 defines thetorque driver receptacle 51 adapted for receiving the male torque driver49 provided at the distal end of the drive stem 46 of the drill head 30.Thus, the inner hub 80 is configured to allow torque to be readilytransferred from the drive stem 46 of the drill head 30 to therotational cutting component 74 of the cutting unit 34.

The rotational cutting component 74 of the cutting unit 34 also includesa plurality of cutting elements mounted at a cutting side 82 (i.e., adistal side) of the front cutter mounting plate 78. The cutting elementsinclude cutting teeth 84 and cutting blades 86 a attached to the cuttingside 82 of the front cutter mounting plate 78. The cutting blades 86 aare mounted adjacent to through-holes 88 that extend through the frontcutter mounting plate 78 in a distal-to-proximal direction. The cuttingblades 86 a are secured to mounting blocks 89 that are secured byfasteners within pockets defined by the front cutting side 82 of therotational cutting component 74. The cutting blades 86 a and/or themounting blocks 89 can be configured to cover at least portions of thethrough-holes 88. In this way, by using different cutting blades 86 a ordifferent sized mounting blocks 89, the maximum available size of theopen portions of the through-holes 88 can be varied to customize thecutting unit 34 to the type of material through which the cutting unit34 is drilling.

The through-holes 88 allow spoils generated by the cutting elements ofthe cutting unit 34 to pass in a distal-to-proximal direction throughthe cutting unit 34. Once the cuttings have passed through thethrough-holes 88, the cuttings are drawn into the vacuum passage 47 andremoved from the bore being drilled. In certain embodiments, thethrough-holes 88 can also allow air to pass in a proximal-to-distaldirection through the cutting unit 34 where the air mixes with thecuttings and is then drawn along with the cuttings back through thethrough-holes 88 in a distal-to-proximal direction to the vacuum passage47.

When drilling in flowable conditions (e.g., below water tableconditions), it may be desirable to be able to selectively open andclose the through-holes 88. When the through-holes 88 are closed, fluidcommunication between the distal end 72 and the proximal end 70 of thecutting unit 34 is blocked so that material on the distal side of thefront cutter mounting plate 78 is prevented from flowing through thethrough-holes 88 and filling the vacuum passage 47 and/or the airpassage 43.

Referring to FIGS. 4 and 5, the cutting unit 34 also includes a shutter90 for selectively opening and closing the through-holes 88. FIGS. 4 and5 show the shutter 90 as an annular plate mounted at the proximal end 70of the cutting unit 34. The shutter 90 includes through-holes 91 thatare circumferentially separated from one another by blocking portions92. The shutter 90 also defines arcuate slots 93 that are definedthrough the blocking portions 92. The slots 93 define radiuses ofcurvature that are swung about a center line that extends along the axisof rotation 75. Fasteners 94 (e.g., shoulder bolts or pins) extendthrough the slots 93 and function to attach the shutter 90 to theproximal side of the front cutter mounting plate 78. The shutter 90 ismounted inside the proximal end of the outer rim 76. The fasteners 94and slots 93 allow the shutter 90 and the rotational cutting component74 to rotate relative to one another about the axis 75 between a firstrelative position shown in FIG. 4 and a second relative position shownin FIG. 5. In the first relative position of FIG. 4, the through-holes91 of the shutter 90 align with the through-holes 88 of the rotationalcutting component 74 such that fluid communication is open between theproximal and distal ends 70, 72 of the cutting unit 34. In the secondrelative position of FIG. 5, the blocking portions 92 of the shutter 90cover the through-holes 88 of the rotational cutting component 74 suchthat fluid communication is blocked between the distal and proximal ends72, 70 of the cutting unit 34.

The cutting unit 34 also includes a retention assembly 23 for retainingthe cutting unit 34 on the drive shaft 46 by preventing the cutting unitfrom sliding distally off of the torque driver 49. The retentionassembly 23 includes a retaining cap 25, a fastener 27 and a centralcutting blade 86 b. The central cutting blade 86 b is attached to a headof the fastener 27. The fastener 27 extends through the retaining cap 25and connects to the end of the drive shaft 46. For example, the fastener27 can include a bolt having a threaded shaft that threads into aninternally threaded axial opening defined by the male torque driver 49of the drive stem 46. When the fastener 27 threads into a threadedopening of the male torque driver 49 (see FIG. 1), the fastener 27causes the back side of the retaining cap 25 to compress/abut againstthe front side of the rotational cutting component 74 thereby preventingthe cutting component 74 from sliding axially off of the male torquedriver 49.

During normal drilling operations, the cutting unit 34 is rotated in afirst rotational direction 95 about the axis of rotation 75. Rotation ofthe rotational cutting component 74 in the first rotational direction 95causes the fasteners 94 to slide within the slots 93 to first ends 96 ofthe slots 93. With the fasteners 94 located at the first ends 96 of theslots 93, the shutter 90 and the rotational cutting component 74 are inthe first relative position in which fluid communication is providedbetween the distal and proximal ends 72, 70 of the cutting unit 34 (seeFIG. 4). As the rotational cutting component 74 continues to be rotatedin the first rotational direction 95 while the fasteners 94 are locatedat the first ends 96 of the slots 93, torque is transferred from therotational cutting component 74 through the fasteners 94 to the shutter90. In this way, the shutter 90 rotates in unison with the rotationalcutting component 74 such that the through-holes 88 remain open.

When drilling operations stop, it may be desirable to close fluidcommunication between the distal and proximal ends 72, 70 of the cuttingunit 34. To accomplish this, the rotational cutting component 74 isrotated in a second rotational direction 97 about the axis of rotation75. As this occurs, the slots 93 and the fasteners 94 allow therotational cutting component 74 to rotate relative to the shutter 90about the axis 75 from the first relative position of FIG. 4 to thesecond relative position of FIG. 5. In the second relative position ofFIG. 5, the fasteners 94 engage second ends 98 of the slots 93 and theblocking portions 92 of the shutter 90 cover the through-holes 88 of therotational cutting component 74. To reopen the through-holes, therotational cutting component 78 is merely rotated in the first direction95 about the axis of rotation 75 causing the rotational cuttingcomponent 74 to move back to the position of FIG. 4.

In alternative embodiments, rather than being used to open and closethrough-holes, shutters in accordance with the principles of the presentdisclosure can be used to adjust the size (e.g., the open transversecross-sectional area) of cutter through-holes to customize thethrough-holes to accommodate drilling in a particular type of material.For example, FIGS. 6-12 show a cutting unit 134 including a rotationalcutting component 174 and a shutter 190. The rotational cuttingcomponent 174 has a front cutting side 182 positioned opposite from aback side 183. A plurality of cutting teeth are provided at the frontcutting side 182, and a plurality of through-holes 188 extend throughthe rotational cutting component 174 from the front cutting side 182 tothe back side 183. The back side 183 of the rotational cutting component174 includes a hub 180 defining a torque driver receptacle 151 adaptedfor receiving the male torque driver 49 provided at the distal end ofthe drive stem 46 of the drill head 30. The hub 180 is configured toallow torque to be readily transferred from the drive stem 46 of thedrill head 30 to the rotational cutting component 174 of the cuttingunit 134. In the depicted embodiment, the torque driver receptacle 151is shown as a torque transfer socket including a plurality of flats. Aretention assembly 123 fastens to the torque driver 49 to prevent thecutting unit 134 from sliding distally off of the torque driver 49. Theretention assembly 123 includes a retaining cap 125 and a fastener 127.The fastener 127 extends through the retaining cap 125 and is adapted toconnect to the torque driver 49. When the fastener 127 is tightened, aback side of the retaining cap 125 clamps against the front side of therotational cutting component 174.

The shutter 190 of the cutting unit 134 is secured to the back side 183of the rotational cutting component 174 by a plurality of fasteners 161.As shown at FIG. 6, the fasteners 161 are depicted as bolts that arethreaded into tapped openings provided at the back side 183 of therotational cutting component 174. The fasteners 161 extend through slots193 defining radiuses of curvature that are swung about a centerlinethat extends along an axis of rotation 175. When the fasteners 161 areloosened, the slots 193 allow the rotational cutting component 174 andthe shutter 190 to be rotated relative to one another about the axis ofrotation 175. In contrast, when the fasteners 161 are tightened, therotational cutting component 174 and the shutter 190 are locked inposition relative to one another such that relative rotational movementbetween the rotational cutting component 174 and the shutter 190 aboutthe axis of rotation 175 is prevented.

The shutter 190 includes through-holes 191 and blocking portions 192. Byrotating the rotational cutting component 174 and the shutter 190relative to one another about the axis of rotation 175, the relativeposition between the through-holes 188 of the rotational cuttingcomponent 174 and the through-holes 191 of the shutter 190 can bealtered. In this way, the amount of open transverse cross-sectional areaprovided by the through-holes 188 can be adjusted. For example, therotational cutting component 174 and the shutter 190 can be locked in afirst relative rotational position (i.e., a fully closed position) (notshown) in which the blocking portions 192 of the shutter 190 fully blockthe through-holes 188 such that material is prevented from passingthrough the rotational cutting component 174. The rotational cuttingcomponent 174 and the shutter 190 can also be locked in a secondrotational position (a fully open position) (see FIGS. 9 and 10) inwhich the through-holes 188 fully align with the through-holes 191 sothat no portions of the through-holes 188 are blocked. In this position,a maximum open transverse cross-sectional area is provided by thethrough-holes 188 for allowing material to pass through the rotationalcutting component 174.

The rotational cutting component 174 and the shutter 190 can also belocked at intermediate positions between the fully open position and thefully closed position. In an intermediate position, the shutter 190 onlypartially blocks the through-holes 188, thereby providing a reducedtransverse cross-sectional area through which material can flow ascompared to the fully open position. In certain embodiments, the shutter190 blocks 10-90 percent of the transverse cross-sectional area of thethrough-holes 188, or 20-80 percent of the transverse cross-sectionalarea of the through-holes 188, or 20-60 percent of the transversecross-sectional area of the through-holes 188 when in selectedintermediate relative rotational positions. It will be appreciated thatthe intermediate relative rotational position can be selected by theoperator so that the open portions of the transverse cross-sectionalareas of the through-holes 188 are selected to match the type ofmaterial through which the drilling apparatus is intended to be drilled,thereby customizing the drilling head to the material intended to bedrilled. The fasteners 161 allow the rotational cutting component 174and the shutter 190 to be locked at an infinite number of intermediaterelative rotational positions. Once the intermediate relative rotationalposition has been set, the fasteners maintain the rotational cuttingcomponent 174 and the shutter 190 in the selected intermediate relativerotational position during drilling. FIGS. 11 and 12 show the rotationalcutting component 174 and the shutter 190 locked in an exampleintermediate relative rotational position in which the through-holes 188are partially blocked by the shutter 190.

The cutting unit 134 is shown including a nut 135 for securing theretention assembly 123 to the rotational cutting component 174 duringstorage and shipping. It will be appreciated that the nut 135 is removedand discarded when the cutting unit 134 is mounted to the drill head 30.

FIGS. 13-15 show still another cutting unit 234 in accordance with theprinciples of the present disclosure. The cutting unit 234 includes arotational cutting component 274 and a shutter 290. The rotationalcutting component 274 includes a front cutting side 282 positionedopposite from a back side 283. Through-holes 288 extend through therotational cutting component 274 from the cutting side 282 to the backside 283. Cutter mounting pockets 285 are provided at the front side 282of the rotational cutting component 274 adjacent to the through-holes288. The cutter mounting pockets allow cutter mounting blocks 289 to bereadily mounted to the rotational cutting component 274 adjacent to thethrough-holes 288. Cutters such as elongated blades are secured to thecutter mounting blocks 289. By selecting different sizes of cuttermounting blocks and/or cutters, the maximum possible open areas of thethrough-holes 288 can be modified. For example, the through-holes 288have a maximum open transverse cross-sectional area when the cuttermounting blocks and the cutters attached thereto do not overlap thethrough-holes 288. By selecting cutter mounting blocks and/or cutterswith a predetermined amount of overlap with respect to the through-holes288, the maximum open transverse cross-sectional area provided by thethrough-holes 288 can be adjusted.

The shutter 290 of the cutting unit 234 includes a hub 235 defining atorque driver receptacle 251 adapted for receiving the male torquedriver 49 provided at the distal end of the drive stem 46 of the drillhead 30. The torque driver receptacle 251 is configured to allow torqueto be readily transferred from the drive stem 46 of the drill head 30 tothe shutter 290. In the depicted embodiment, torque driver receptacle251 includes a socket configuration including a plurality of flats. Aretention assembly 223 is used to prevent the rotational cuttingcomponent 274 and the shutter 290 from sliding distally off of thetorque driver 49. The retention assembly 223 includes a retaining cap225, a fastener 227 and a central cutting blade 286 b. The centralcutting blade 286 b is attached to a head of the fastener 227. Thefastener 227 extends through the retaining cap 225 and connects to theend of the drive shaft 46. For example, the fastener 227 can include abolt having a threaded shaft that threads into an internally threadedaxial opening defined by the male torque driver 49 of the drive stem 46.

The retaining cap 225 is configured to retain the rotational cuttingcomponent 274 and the shutter 290 on the drive shaft 46 without clampingthe rotational cutting component in place relative to the shutter 290.For example, the retaining cap 225 includes a hub portion 221 and aflange portion 219 that projects radially outwardly from a front end ofthe hub portion 221. The rear end of the hub portion 221 defines ashutter clamping surface 221 a that engages a front face of the hub 235of the shutter 290 when the fastener 227 is threaded into the driveshaft 46 to retain the shutter 290 on the drive shaft 46. The rear sideof the flange portion 219 defines a rotational cutting componentretention surface 219 a that opposes the front side of the rotationalcutting component 274 to prevent the rotational cutting component 274from disconnecting from the drive shaft 46. The hub portion 221 definesan offset 217 between the shutter clamping surface 221 a and therotational cutting component retention surface 219 a. The offset 217extends in a front-to-rear direction and provides a gap between thesurfaces 221 a, 219 a in which an inner portion 290 i of the shutter 290is received. The gap provided by the offset 217 is larger than thenthickness of the inner portion 290 i and prevents the inner portion 290i from being clamped by the retaining cap 225 when the fastener 227 istightened. In this way, the retention assembly 223 does not interferewith the ability of the rotational cutting component 274 to rotaterelative to the shutter 290 about an axis of rotation 275.

The cutting unit 234 also includes slide pins 294 (e.g., dowel pins)having front ends inserted within openings defined by the back side 283of the rotational cutting component 274 (see FIG. 15). Rear ends of theslide pins 294 fit within corresponding arcuate slots 293 defined by theshutter 290. The arcuate slots 293 have curvatures defined by radiusesswung about a centerline that extends along the axis of rotation 275.The slide pins 294 serve two primary functions. First, the slide pins294 allow torque to be transferred from the shutter 290 to therotational cutting component 274 when torque is applied to the shutter290 by the drive stem 46 of the drill head 30. Thus, during drilling,torque for rotating the rotational cutting component 274 about the axisof rotation 275 is provided by the drive stem 46 and is transferred fromthe shutter 290 to the rotational cutting component 274 through theslide pins 294. The rotational cutting component 274 and the shutter 290are rotated in unison about the axis of rotation 275 by the drive shaft46 during drilling operations. The slide pins 294 and the slots 293 alsoallow the shutter 290 and the rotational cutting component 274 to berotated relative to one another about the axis of rotation 275. In thisway, similar to the first embodiment described herein, the rotationalcutting component 274 and the shutter 290 can be moved to a firstrelative rotational position in which through-holes 291 of the shutter290 align with the through-holes 288 of the rotational cutting component274 such that the through-holes 288 are open to allow material to passin a front-to-back direction through the cutting unit 234. The slidepins 294 and the slots 293 also allow the rotational cutting component274 and the shutter 290 to be moved to a second relative rotationalposition in which the shutter 290 blocks the through-holes 288 bypreventing material from passing through the cutting unit 234 in afront-to-back action.

The cutting unit 234 further includes a bearing member 211 that mountsbetween the rotational cutting component 274 and the shutter 290. Thebearing member 211 includes a radial bearing portion 211 a that fitsover the hub 235 of the shutter 290 and provides a radial bearingbetween a outwardly radially facing surface of the shutter hub 235 andan inwardly radially facing surface of the rotational cutting component274. The bearing member 211 also includes an axial/thrust bearingstructure 211 b that forms a bearing between a front side of the shutter290 and the back side 283 of the rotational cutting component 274.

The cutting unit 234 is shown including a nut 213 for securing theretention assembly 223 to the rotational cutting component 274 and theshutter 290 during storage and shipping. It will be appreciated that thenut 213 is removed and discarded when the cutting unit 234 is mounted tothe drill head 30.

In the embodiment of FIGS. 13-15, drilling ideally takes place when thecutting unit 234 is rotated in a rotational direction 297 about the axisof rotation 275. Rotation of the shutter 290 by the drive shaft 46 inthe rotational direction 297 causes the slide pins 294 to slide withinthe slots 293 to ends 298 of the slots 293. With the slide pins 294located at the ends 298 of the slots 293, the shutter 290 and therotational cutting component 274 are in the open position in which fluidcommunication is provided between the front and back sides of thecutting unit 234. As the shutter 290 continues to be rotated in therotational direction 297 while the slide pins 294 are located at theends 298 of the slots 293, torque is transferred from the shutter 290 tothe rotational cutting component 274 by the slide pins 294. In this way,the rotational cutting component 274 rotates in unison with the shutter290 such that the through-holes 288 remain open.

When drilling operations stop, it may be desirable to close fluidcommunication between the front and the back sides of the cutting unit234. To accomplish this, the shutter 290 is rotated by the drive shaft46 in a rotational direction 295 about the axis of rotation 275. As thisoccurs, the slots 293 and the slide pins 294 allow the shutter 290 torotate relative to the rotational cutting component 274 from the openposition to the closed position. In the closed position, the slide pins294 engage ends 296 of the slots 293 and blocking portions of theshutter 290 cover the through-holes 288 of the rotational cuttingcomponent 274. To re-open the through-holes 288, the shutter 290 ismerely rotated in the direction 297 about the axis of rotation 175,causing the shutter 290 to move relative to the rotational cuttingcomponent 274 back to the open position. One advantage of this versionof the cutting unit is that contact between the cutting teeth of therotational cutting component 274 and the ground provides resistance thatprevents the shutter 290 and the rotational cutting component 274 fromrotating in unison with one another when it is intended or desired toclose the through-holes by rotating the shutter 290 in the direction 295relative to the rotational cutting component 274.

From the foregoing detailed description, it will be evident thatmodifications and variations can be made in the devices of thedisclosure without departing from the spirit or scope of the invention.

1. A drilling apparatus comprising: a rotational cutting componentincluding a front cutting side and a back side, the rotational cuttingcomponent defining a plurality of through-holes that extend through therotational cutting structure from the front cutting side to the backside; a shutter mounted adjacent to the back side of the rotationalcutting component, the shutter and the rotational cutting componentbeing rotationally movable relative to one another about an axis betweena first orientation where the shutter blocks the through-holes and asecond orientation wherein the through holes are open, the shutterincluding a torque transfer interface aligned with the axis fortransferring torque from a drive shaft to the shutter to rotate theshutter about the axis; and a connection arrangement between the shutterand the rotational cutting component for transferring torque from theshutter to the rotational cutting component to rotate the rotationalcutting component about the axis, the connection arrangement alsoallowing a range of relative rotational movement between the rotationalcutting component and the shutter about the axis, the range of relativerotational movement allowing the rotational cutting component and theshutter to be moved between the first and second orientations.
 2. Thedrilling apparatus of claim 1, wherein the connection arrangementincludes slide elements that extend through curved slots that curveabout the axis.
 3. The drilling apparatus of claim 2, wherein the slideelements include slide pins affixed to the rotational cutting component,and wherein the curved slots are defined by the shutter.
 4. The drillingapparatus of claim 3, wherein the curved slots do not extend completelythrough the shutter.
 5. The drilling apparatus of claim 1, wherein theshutter is at least partially recessed within the back side of therotational cutting component.
 6. The drilling apparatus of claim 1,wherein a thrust bearing is mounted between the rotational cuttingcomponent and the shutter.
 7. The drilling apparatus of claim 1, whereincutters are mounted at the front cutting side of the rotational cuttingcomponent.
 8. The drilling apparatus of claim 7, wherein the cutters canbe mounted to the front side of the rotational cutting component withmounting blocks, wherein the cutter mounting blocks are secured to therotational cutting component adjacent to the through-holes, and whereindifferent sized mounting blocks can be used to vary maximum open sizesof the through-holes.
 9. A drilling apparatus comprising: a rotationalcutting component including a front cutting side and a back side, therotational cutting component defining a plurality of through-holes thatextend through the rotational cutting structure from the front cuttingside to the back side, the rotational cutting component being rotatedabout an axis during drilling; and a blocking component mounted adjacentto the back side of the rotational cutting component for blocking atleast portions of the through-holes, the blocking component beingmountable to the rotational cutting component in different rotationalpositions about the axis, wherein the blocking component provides adifferent through-hole blockage percentage at each rotational position.10. The drilling apparatus of claim 9, wherein the blocking component issecured in the rotational positions by fasteners.
 11. The drillingapparatus of claim 10, wherein the fasteners extend through curved slotsdefined by the blocking component.
 12. The drilling apparatus of claim11, wherein the curved slots have curvatures centered about the axis.13. A drilling apparatus comprising: a cutting unit defining at leastone through-hole that provides fluid communication between a distal sideand a proximal side of the cutting unit, the cutting unit including aplurality of cutting elements at the distal side of the cutting unit;and a shutter for selectively opening and blocking the through-hole ofthe cutting unit.
 14. A drilling apparatus comprising: a cutting unitdefining at least one through-hole that provides fluid communicationbetween a distal side and a proximal side of the cutting unit, thecutting unit including a plurality of cutting elements at the distalside of the cutting unit; and a shutter used to at least partially coverthe through-hole.